1. Field of the Invention
The present invention relates to an apparatus and method for generating coded high-frequency signals wherein the apparatus includes a converter for converting a non-electrical primary energy into low-frequency electrical energy, an element for converting the low-frequency electrical energy into a high-frequency signal, and a coding device for generating a coded signal from the high-frequency electrical signal.
2. Description of the Prior Art
It is known to generate high-frequency energy signals with the aid of low-frequency electrical energy; e.g., direct current (battery), power supply frequency current and similar energy from similar energy sources. Radio-frequency transmitters fed from the power supply and battery-driven RF transmitters such as radio transceivers, mobile telephones or cordless telephones are widely known. Such apparatuses enable non-coded, but preferably coded/modulated, high-frequency signals to be emitted for diverse radio information transmissions. For the cases of battery operation, solar energy also may be used as the primary energy source, with the aid of which, given the presence of sufficient illumination, a rechargeable battery or an accumulator can be recharged or kept in its charge state.
It is also known for physical and similar data, measurement variables, etc., to be interrogated remotely. One example of such remote interrogation is a remote thermometer by means of which the temperature, such as that of a hot boiler, is measured and displayed at a location remote from the boiler. For this purpose, a remote thermometer that operates purely electrically has a two-core electrical line between the temperature-sensitive sensor and the actual display device.
Equipment which can be interrogated remotely and in which the connection between sensor and display device is a radio transmission are also known. Although the data transmission takes place in a wirefree manner, a source for electrical energy is nevertheless necessary at the location of the sensor, namely for the transmitter. If the connection is intended to be completely wirefree, electrical battery energy feeding is used at the location of the data interrogation (unless an electrical source is otherwise available there). Furthermore, equipment which can be interrogated remotely without an electrical supply at the sensor are known. In the case of which the energy necessary for the data transmission is coupled in a wirefree manner, by means of a correspondingly high-energy and broadband interrogation pulse, into a surface wave device. From there it is sent back passively after suitable signal processing. What is disadvantageous about this, however, is the fact that the high-energy interrogation pulse has to be emitted regularly and all the more often the more accurately the measurement variable is to be determined or observed.
An object of the present invention is to specify, for a relatively specific operating case, the advantageously applicable generation of the electrical energy necessary for such a transmitter. This relatively specific operation involves carrying out a radio information transmission only in relatively short time intervals of interest, wherein the length of a respective time interval of this type is short (e.g., only 1 thousandth or less) relative to the pauses between such successive time intervals.
Accordingly, the present invention is based on the concept, preferably from the viewpoint of reducing the technical outlay and also of minimized maintenance, of finding a principle which enables a completely sufficient radio information transmission for the respective case, with energy other than electrical primary energy being expended.
In advance of the descriptions of individual examples, the principle underlying the present invention shall be briefly delineated, those parts of the description which then follow will serve to provide a more in-depth understanding of such principle.
The case of photovoltaic conversion already has been mentioned which, however, as is known and evident, can be made usable only to a limited extent. It is dependent on sufficient incidence of light and usually can be used only in conjunction with energy storage elements, or accumulators.
The present invention is geared to using energy that is available, occasionally even in a very large quantity and being referred to here as primary energy available from the surroundings, in order to provide electrical energy for generating a high-frequency signal (radio signal. Such primary energies that usually are not used are mechanical deformation energy, in particular pressure or other forces, friction forces (low-temperature), thermal energy, acceleration forces, radiation, oscillating masses and the like. Insofar as forces are referred to here, their temporal or local gradient is used for the present invention, the gradient being equivalent to an energy.
Examples of previously unused primary energies that may be and [lacuna] are the pressure/deformation energy fundamentally necessary for actuating an electrical switch, heat, e.g. from a radiator, that is available with a spatial or temporal temperature gradient and acceleration energy of an oscillating seismic mass, e.g., such as that in a vehicle. Other suitable primary energies are shaking, vibrating, and air movements. This exemplary enumeration is not exhaustive in relation to the present invention and must in no way be seen as a restriction of the application of the principle of the invention.
The integral principle of the present invention essentially consists in tapping off a proportion of energy from such process energy and converting such proportion of energy firstly into low-frequency electrical energy as defined here. In the most general form, according to the present invention, this is understood to mean in the first instance the separation of charges, as arises, e.g., as electrostatic charging due to friction. According to the present invention, the generation of a voltage having a slowly rising amplitude is also understood to be low-frequency. The voltage generated in pyroelectric or piezoelectric and also in photovoltaic components also be used in accordance with the present invention.
A next step is to transform this so-called low-frequency electrical energy into high-frequency electrical energy. For this purpose, an element with a nonlinear characteristic curve (nonlinear element) may be used in accordance with the present invention. Connection therewith this is understood to mean an element whose behavior changes abruptly as a function of the applied voltage starting from a specific limit value or in a limit value range. As a result, such an element generates a current pulse with a steep edge, which corresponds to a high-frequency signal in the frequency domain.
Depending on the bandwidth of this high-frequency signal, it may be necessary to filter out a narrower-band frequency spectrum from such signal. However, it is also possible to use a nonlinear element which already generates a sufficiently narrowband high-frequency signal by itself. This enables the full energy content of the high-frequency signal to be used.
A further step of the present invention is to code this high-frequency electrical energy with an information item and emit it as a coded (narrowband) high-frequency signal. This coding may be suitable for identification purposes and/or may also contain other information items; e.g., items concerning the nature and size of parameters acting on the coding device. These may be specific physical quantities such as, for instance, a temperature, a force or a sudden impedance change, or they may be chemical or biological parameters as well; e.g., concentration and/or nature of gases, vapors, liquids, substances or biological material such as viruses or genes.
A coded high-frequency signal is emitted, whose energy content, with narrowband selection being performed if appropriate, is necessarily relatively low but, nevertheless, sufficiently large within the scope of application of the present invention. It is surprising that, in spite of a low degree of conversion of the primary energy used into the energy of the coded high-frequency signal that is generated, there is no problem at all with respect to the beneficial application of the present invention.
In this respect, it should be pointed out that the radio receiving station (positioned at an appropriately limited distance) is designed and configured in a manner known, per se, such that it can detect the information of the received (coded) narrowband high-frequency signal. This is not a problem at the radio receiving end because the energy supply of the receiver can be ensured in a conventional manner; e.g., by means of an electricity power supply, batteries or the like.